Many types of work vehicles utilize what is referred to as a power take-off (PTO) shaft for the operation of equipment and implements that are attached to or towed behind the work vehicles. Agricultural vehicles such as the range of tractors available for use by farmers often employ power take-off shafts. The power take-off shaft provides for the power linkage and the transmission of mechanical power from the tractor's engine to the attached implement or piece of equipment. The power take-off shaft provides operational power for the implement, and this can include turning or rotating blades of the implement or powering the conveyor belt or system of the implement. Among the common pieces of equipment or machinery that can be driven from the power take-off are balers, mowers, grinders, augers, grinder mixers, manure pumps, forage (chopper) boxes, power boxes, hay rakes, and various types of wagons. In addition, some types of equipment and machinery are hydraulically operated, and the use of the power take-off shaft can be used to supply the power for their hydraulic operation. Such machinery includes, for example, hydraulic dump wagons and trailers; implements having discs that must be raised and lowered for transport; and wood splitters that employ hydraulic cylinders for running a blade or cutter.
In many cases the implement or machinery must be removed or hauled from the field by a vehicle, such as a pickup truck, and then unhooked from the pickup truck and hooked to the tractor—with the power take-off—for unloading the contents of the implement or undertaking further processing at feed mills or fertilizer plants. In addition, tractors are specialized types of vehicles, and are not conducive to traveling on regular roads and highways, let alone towing or hauling farm implements and machinery on such roads and highways. Yet such towing or hauling loads or produce is common, and it is desirable to have a power take-off assembly available for unloading the contents when the destination is reached (which can be a field on another part of the farm or feed or grain storage silos). Thus, it is desirable to have a power take-off unit available that is mounted to or operated from vehicles other than tractors. Moreover, it is desirable to have a portable power take-off unit for supplying mechanical power to non-powered construction or farm implements and machinery that are located at the work site or field and remote from a power source. Thus, the prior art discloses a number of power take-off systems and assemblies.
For example, the Ham patent (U.S. Pat. No. 3,817,413) discloses a demountable attachment for a load-carrying vehicle that includes a demountable body having wheels that roll along longitudinal members on the vehicle chassis for loading and unloading the body. The body also includes retractable legs that support the body when it's dismounted from the vehicle.
The Dehn patent (U.S. Pat. No. 3,883,020) discloses a framework that can be removably mounted onto the bed of a pickup truck and which includes detachable and retractable legs that facilitate the loading of the framework onto the pickup truck and the freestanding support of the framework when unloaded from the truck.
The Ward patent (U.S. Pat. No. 5,690,182) discloses a triangular-shaped frame for pivotal connection to the hitch members of a three-point hitch system mounted to the rear of a tractor. The frame includes a tube socket to which a hitch ball-type connection can be attached.
The Stelzle et al. patent (U.S. Pat. No. 6,134,494) discloses an automatic power takeoff control system for controlling the engagement of a power take-off shaft of a work vehicle having a hitch.
The Spears patent (U.S. Pat. No. 6,148,928) discloses a three-point hitch mounting system that includes hydraulically actuated draft arms for raising and lowering farm implements and a power take-off shaft for driving implements such as a mower.
The Spears patent (U.S. Pat. No. 6,481,948 B2) discloses a frame apparatus for disposition on the bed of a pickup truck and which accepts and operates implements such as off-the-shelf front-end loader assemblies.
However, despite the ingenuity of the above devices, there remains a need for a portable self-powered power take-off unit that can be easily transported and set up in several minutes at the rear of a pickup truck and is also adaptable as a stand-alone power take-off unit.